Method of obtaining ultra-violet rays by spark discharge.



J. VON KOWALSKI-WIERUSZ. METHOD OF OBTAINING ULTRA-VIOLET RAYS BYSPARKDISCHARGE.

APPLICATION FILED APR. 10. I914. LQW $%?O Patented Dem, I916.

1/776 w/7'e f/vm AG.

I I I r L,

UT T TWM.

METHOD OF OBTAINING ULTRA-VIOLET RAYS BY SPARK DISCHARGE.

, moment.

Specification of Letters Patent.

Patented 10cc. 5, 19110..

Application filed April 10, 1914. Serial No. 831,060.

To all whom'it may concern:

Be it known that I, JosEPH VON KowAL- SKI-WIERUSZ, citizen ofAustria-Hungary, residing at Fribourg, Switzerland, have inventedcertain .new and useful Improvements in Methods of ObtainingUltra-Violet Rays by Spark Discharge, of which the following is aspecification.

For the purpose of obtaining ultra-violet rays for industrial purposesit has been usual to employ as the source of the rays almost exclusivelythe arc lamp, for example, in the case of Finsen light, the ironarc-lamp, and in other cases the mercury arc-lamp, while the knownmethod of obtaining the rays from the oscillating spark has not usuallybeen employed since the ultra-violet rays so obtained are too costly inproportion to the energy expended in the creation of the sparkgap.

As a series of scientific investigations have shown, distinction must bemade between three different zones of ultra-violet rays, correspondingto the effects which the rays produce. The first zone, or the initialultraviolet, extends from the visible spectrum to about a wave-length of3000 Angstrom units. The radiation which corresponds to the rays of thiszone is abundantly emitted by the sun. It is but slightly absorbed bythe atmosphere. The photo-chemical reactions which this radiationproduces are exothermic almost without exception. The physiological andbiological properties are similar to those of the adjacent blue andviolet radiation, but more intense. This radiation exerts almost nodestructive action on the lower forms of life, such as bacteria. Thesecond zone comprises the so-called middle ultra-violet; and extendsfrom about 3000 A to 2000 A. Only the first part of this zone is foundin sunlight. The rays of this zone are strongly absorbed by manysubstances, and therefore the photochemical effects of this radiationare very intense. There is known a whole series of endothermic chemicalreactions which are produced at the expense of this radiation.Biologically they are bactericidal and coagulate albumin. Finally, thethird zone, the extreme the commercial production of the middleultra-violet rays and the object of the invention is to enable suchultra-violet rays to be economically obtained in the spark gap.

These radiations between 2800 and 2200 A are preminently effective forsterilization purposes for the following reasons: The investigations ofM. Henry have shown that the shorter the wave-length, the more intenseis the bactericidal action of the radiations and other investigationshave shown that the calcium ion strongly absorbs the short wave-lengths.In consequence of this, rays of less than 2200 A are not to beconsidered in the sterilization of drinking water, which contains moreorless calcium.

According to the present invention the method consists in employing aconsiderable dampingof the spark gap, as high a current amplitude aspossible and a wave length of less than 3000 meters for the oscillationcreating the sparks. These conditions may be fulfilled by the usualscientific means at disposal.

The drawing is a diagramof a conventional apparatus for carrying out themethod. In the drawing the source of current is represented byalternating current mains feeding into a primary circuit containing theusual Wattmeter, adjustable inductance and resistance. There is alsoplaced in this circuit the primary of a resonance transformer whosesecondary is connected in the oscillation circuit which contains thearcs and condensation battery. The electrical constants of theoscillation circuit are preferably such that its period corresponds to awave length less than 3000 meters.

The desired damping is obtained, for example, by the use of a suitablematerial for the electrodes which moreover also energetically emits inthis sphere ultra-violet rays. Such material may for example be nickel,cobalt and alloys of these two metals with other metals and especiallywith the metals of the rare earths. Moreover zirconium, tungsten andmolybdenum may be employed when the discharge takes place in an inertgas. such as hydrogen or nitrogen. But any other agent increasing thespark decrement can be employed for this purpose as, for example, theinjection of a gas jet into the spark gap or the like.

The greatest possible current amplitude for a given tension amplitude,dependent on the electrode material, is obtained in the known manner by,suitable selection of the electric constants of the oscillatory circuitin which the spark is formed.

By extensive experiment it has been shown that the number of spectrallights is not only dependent on the capacity and self-induction used butalso on all the electrical conditions of the oscillating circuit and, asregards the radiant energy of difl'erent parts of the ultraviolet beinginfluenced in a different manner by suitable conditions of the circuit,a series of tests demonstrated:

l. With the increase of the maximum amplitude of current in theoscillation circuit the zone which corresponds to the maximum of radiantenergy is displaced toward the shorter wave-lengths.

2. In spark gaps, in which the so-called spark damping is greater, thewave-length which corresponds to the maximum of radiant energy isshorter than for spark gaps with less damping. This result can be takenas indicating that the maximum radiation of energy is displaced towardshort wavelengths if much energy is consumed in the spark gap. a

3. Finally, research has shown that with different electrodes theposition of the maximum of radiant energy in the spark was verydependent upon the electrode material and, in particular, is diflerentfor an alloy oftwo metals than might be deduced from the investigationswith the pure metals.

Therefore in order to obtain a'favorable efficiency of radiation in themiddle ultraviolet, as great as possible amplitude of current must firstbe obtained in the oscillation. This, however, is dependent upon thecapacity, as well as the self-induction of the oscillating circuit, sothat the capacity must be as great as possible and the self-induction assmall as possible. For an industrial installation it is,however,.compulsory, in increasing the capacity, also to increase theself-induction (in consequence of the selfinduction of the condensersthemselves, as well as the connecting wires which must be used betweenthe condensers).

In regard to the spark damping, investigations have shown that it isdependent on the spark material. (See Lehrbuch do? DrahtlosenTelegraphic, by J. E. Zonneck 1913). Further I have found that the sparkdamping is greater with certain alloys, as for example, invar, than withthe pure metals. On the other hand, however, it was found that the sparkdamping alone is not sufficient to produce an appreciable radiation ofenergy in the middle ultra-violet. Different metals or metallic alloyspossess, in this zone, a different specific capability for radiation,which latter is not always parallel with the great damping. Metals andmetallic alloys must be used which simultaneously show, under givenelectrical conditions, great spark damping and great specific capabilityfor radiation for the middle ultra-violet.

The improved method is as hereinbefore noted particularly economical inthe production of those ultra-violet rays which lie in the part mosteflective for example for sterilizing purposes, that is, for rays ofless than 3,000 p. p. wave length.

In the employment of the rays for sterilization, chemical actions orother purposes it is in many cases necessary or at least desirable toprevent the action of the oxidation of the nitrogen which takes place inthe spark gap upon the substances to be treated with the rays. In suchcases a film is placed between the spark gap and the substances to betreated which is transparent to ultraviolet rays but keeping back theoxids and the like. This may be efiected by arranging a casing of quartzglass around the spark gap.

1. The method of obtaining ultra-violet rays from an oscillatory sparkwhich consists inconsiderably damping the spark, employing a highcurrent amplitude and employing spark oscillations whose wavelength isless than 3000 meters.

2. The method of obtaining ultra-violet rays from an oscillatory sparkwhich consists in considerably damping the spark, employing a highcurrent amplitude by suitable selection of the electric constants of t eoscillatory circuit in which the spark is generated, and employing sparkoscillations whose wave-lengthis less than, 3000 meters.

3. The method of obtaining ultra-violet rays from an oscillatory sparkwhich consists in the use of metal electrodes adapted to considerablydamp the spark, employing a high current amplitude and employing sparkoscillations Whose wave-length is less than 3000 meters.

4. The method of obtaining ultra-violet rays from an oscillatory sparkwhich con sists in the use of electrodes of an alloy adapted toconsiderably damp the spark, em-

naoaeaa v ploying a high current amplitude and emcuit in which the sparkis generate& and 10 ploying spark oscillations whose waveemploying sparkoscillations whose wavelength in less than 3000 meters. length is lessthan 3000 meters.

5. The method of obtaining ultra-violet In testimony whereof ll affix mysignature rays from an oscillatory spark which conin presence of twowitnesses sists in the use of electrodes adapted to con- PROF. DR.JOSEPH vor KOWALSKI-WIERUSZ. siderably damp the spark, employlng a highWitnesses: current amplitude by suitable selection of Konsns- JUTTSON,

the electric constants of the oscillatory cir- F. SCININGER.

